Hmm. That's a first. If its the proper firmware for the proper difference and it's the latest version of RedSn0w and all, it should have a problem. Try using iTunes again, and make sure it's in dfu
Well, I had an iPhone 3GS but after the years it just gone completely off with all sorts of trouble including not being able to restore. The worse thing is that the battery drains off like in a 2 hours without any usage. Just get the new iPhone 5 perhaps?